Mage/Boomkin is a pretty awful 2V2 combo & gets shit on by any dk/healer n rogue/Healer in which the players have figured out how to chain up defensive cooldowns (aka like 2K rating).
Mage/Boomkin/Priest is pretty strong though, but the hardest part is actually finding a boomkin that wants to run it, seeing as they all just play LSD2 & probably will do so even more after the patch.